This project is an investigation of acyl transfer reactions of amidines at both nonenzymatic and enzymatic levels. The kinetics and mechanisms of the aminolysis of diphenylformamidine provides evidence that there is a tetrahedral addition intermediate on the reaction pathway and that proton transfer steps may be involved in the rate limiting steps. On the enzymatic level, the formimino transferase from hog liver has been purified by affinity chromatography and initial rate studies have shown a sequential mechanism of action. The data indicate that both cyclodeaminase and formiminotransferase activity are catalyzed by the same enzyme molecule. Further kinetic studies are in progress to confirm these conclusions and establish the kinetic mechanism in greater detail.